我的伴侣较早时没有运气，所以我想我会尝试的。我们这里有一个正在使用的程序正在导致一个无限循环的问题，我们无法弄清楚。基本上，该程序是针对电影租赁商店的雇员的，要求他提供8个不同的选项，他可以选择一个选项，作为回报，该选项将执行特定的代码路径。提示之一是“退出”选项，简而言之，我们希望员工继续提示他想要的选项，该选项将执行任何代码，直到该员工选择提示8退出并因此终止程序。相反，我们在员工选择的每个选择中都会遇到一个无限循环。例如，如果他选择提示1来显示所有电影，则它会不断地反复显示电影。任何有关如何解决此问题的建议将不胜感激。
import java.sql.*;
import java.util.Scanner;
public class MovieRentalDatabase {
public static void main(String[]args){
Scanner input = new Scanner(System.in);
Connection conn = null;
try
{
conn =
DriverManager.getConnection("jdbc:mysql://cs.neiu.edu:3306/18f315_Cody?serverTimezone=UTC&" +
"user=18f315_Cody&password=");
Statement stmt = conn.createStatement();
System.out.println();
System.out.println("Welcome To Windy City Video Employee Portal");
System.out.println();
System.out.println("Menu Choices: ");
System.out.println("1. List All Movies Available");
System.out.println("2. List All Customers From Rental Database");
System.out.println("3. Add a New Movie To List");
System.out.println("4. Enroll a New Member");
System.out.println("5. Search Movies");
System.out.println("6. Delete Movies From Store");
System.out.println("7. Search For A Member ");
System.out.println("8. Quit.");
System.out.println();
System.out.print("Enter your choice: ");
int a = input.nextInt();
System.out.println();
int countmin =13;
int countmax = 15;
while(a != 8)
{
while(a < 1 || a > 8)
{
System.out.println("Choice Entered is Invalid!");
System.out.println("Please Try Again");
System.out.print("Enter your choice: ");
a = input.nextInt();
System.out.println();
}
//If user input is 1
if(a == 1)
{
String sql3 = "SELECT * FROM Movie";
ResultSet rs = stmt.executeQuery(sql3);
while(rs.next()){
int movieID = rs.getInt("MovieID");
String movieName = rs.getString("MovieName");
Date release = rs.getDate("releaseDate");
//display values from the sql statements from above
System.out.println("MovieID: " + movieID);
System.out.println("Movie Name: " + movieName);
System.out.println("Release Date: " + release);
System.out.println();
}
rs.close();
}
//If user input is 2
if(a == 2)
{
String sql4 = "SELECT * FROM MemberSignUp";
ResultSet rs1 = stmt.executeQuery(sql4);
while(rs1.next()){
int memberID = rs1.getInt("MemberID");
String firstName = rs1.getString("FirstName");
String lastName = rs1.getString("LastName");
//display values from the sql statements from above
System.out.println("MemberID: " + memberID);
System.out.println("First Name: " + firstName );
System.out.println("Last Name: " + lastName);
System.out.println();
}
rs1.close();
}
//If user input is 3
if(a == 3)
{
input.nextLine();
System.out.print("Enter a New MovieID Number: ");
String sql5 = input.nextLine();
System.out.print("Enter The Movie Name: ");
String sql6 = input.nextLine();
System.out.print("Enter The Release Date: ");
String sql7 = input.nextLine();
String sql8 = "INSERT INTO Movie VALUES(" + sql5 + "," + "'" + sql6 + "'" + "," + "'" + sql7 + "');";
stmt.executeUpdate(sql8);
}
//If user input is 4
if(a == 4)
{
input.nextLine();
System.out.print("Enter a New MemberID Number: ");
String sql9 = input.nextLine();
int result = Integer.parseInt(sql9);
while(result <= countmin || result >= countmax)
{
System.out.println();
System.out.println("You Have Entered a MemberID That Already Exists!");
System.out.println("Please use " + (countmin + 1) + " as the new MemberID");
System.out.println();
System.out.print("Enter a New MemberID Number: ");
sql9 = input.nextLine();
result = Integer.parseInt(sql9);
}
System.out.print("Enter First Name: ");
String sql10 = input.nextLine();
System.out.print("Enter Last Name: ");
String sql11 = input.nextLine();
String sql12 = "INSERT INTO MemberSignUp VALUES(" + sql9 + "," + "'" + sql10 + "'" + "," + "'" + sql11 + "');";
stmt.executeUpdate(sql12);
countmin++;
countmax++;
}
//If user input is 5
if(a == 5)
{
input.nextLine();
System.out.print("Enter MovieID Number: ");
String sql15 = input.nextLine();
System.out.print("Enter Movie Name: ");
String sql14 = input.nextLine();
System.out.println();
String sql16 = "Select MovieID, MovieName, releaseDate from Movie Where MovieName = " + "'" + sql14 + "'" + "or MovieID = " + "'" + sql15 + "'" ;
ResultSet rs2 = stmt.executeQuery(sql16);
while(rs2.next()){
int mID = rs2.getInt("MovieID");
String mName = rs2.getString("MovieName");
Date release1 = rs2.getDate("releaseDate");
System.out.println("MovieID: " + mID);
System.out.println("Movie Name: " + mName);
System.out.println("Release Date: " + release1);
System.out.println();
}
rs2.close();
}
//If user input is 6
if(a == 6)
{
input.nextLine();
System.out.print("Enter MovieID Number: ");
String sql17 = input.nextLine();
System.out.print("Enter Movie Name: ");
String sql18 = input.nextLine();
System.out.println();
System.out.println("Movie Sucessfully Deleted!");
String sql19 = "DELETE FROM Movie Where MovieID = " + "'" + sql17 + "' AND MovieName = '" + sql18 + "'";
stmt.executeUpdate(sql19);
}
//if user input is 7
if(a == 7)
{
input.nextLine();
System.out.print("Enter MemberID Number: ");
String sql20 = input.nextLine();
System.out.print("Enter First Name: ");
String sql21 = input.nextLine();
System.out.print("Enter Last Name: ");
String sql22 = input.nextLine();
String sql23 = "Select MemberID, FirstName, LastName from MemberSignUp Where MemberID = " + "'" + sql20 + "'" + "or FirstName = " + "'" + sql21 + "'" + "or LastName = " + "'" + sql22 + "'" ;
ResultSet rs3 = stmt.executeQuery(sql23);
System.out.println();
while(rs3.next()){
int member = rs3.getInt("MemberID");
String memberName = rs3.getString("FirstName");
String memberLast = rs3.getString("LastName");
System.out.println("MemberID: " + member);
System.out.println("First Name: " + memberName);
System.out.println("Last Name: " + memberLast);
System.out.println();
}
rs3.close();
}
//If user input is 8
if(a == 8)
{
System.out.println();
System.out.println("Enjoy The Rest Of Your Day!");
System.exit(0);
}
}
}catch (SQLException ex)
{
// handle any errors
System.out.println("SQLException: " + ex.getMessage());
System.out.println("SQLState: " + ex.getSQLState());
System.out.println("VendorError: " + ex.getErrorCode());
}
}
}
答案 0 :(得分：0)
移动所有这些行：
System.out.println("Menu Choices: ");
System.out.println("1. List All Movies Available");
System.out.println("2. List All Customers From Rental Database");
System.out.println("3. Add a New Movie To List");
System.out.println("4. Enroll a New Member");
System.out.println("5. Search Movies");
System.out.println("6. Delete Movies From Store");
System.out.println("7. Search For A Member ");
System.out.println("8. Quit.");
System.out.println();
System.out.print("Enter your choice: ");
a = input.nextInt();
System.out.println();
紧接着：
while (a != 8) {
因此，在每次迭代的开始，都会向用户显示菜单。
在while循环之前，初始化变量a：
int a = 0;
从int中删除int a = input.nextInt();
您的代码太长，无法测试，但是我认为这可以解决无限循环问题。